Conventionally, when information such as moving image data, still image data, audio data, and the like included in a recording medium such as an optical disk, magnetic disk, magnetooptical disk, or the like is to be handled by an application such as image display software, digital album software, or the like, information on the recording medium (disk) is directly accessed via a file system such as UDF, FAT, or the like, as shown in FIG. 17.
In a print mode, list display mode, slideshow mode, or the like, in a case where a plurality of files must be grouped, a management file such as a playlist file, DPOF file, or the like, which describes files that belong to a group and required information, is generated for each group, and individual grouping files are managed by a corresponding management application.
In recent years, video cameras using a hard disk, magnetic disk, and the like as recording media have begun to be put into the market. Since such video camera using the recording medium can store respective scenes as files on the recording medium, respective scenes can be relatively easily and quickly accessed in a playback mode.
As a playback display method of the video camera that uses the recording medium, still image indices are recorded in files of respective scenes, and are displayed as a list. An image file selected from the list is displayed on a display device such as an LCD, EVF, or the like of a video camera main body, or is output as a moving image via a monitor output terminal. The volume of information recorded on a recording medium largely differs depending on the image quality and resolution upon recording. With the technical advances, the capacity of the recording medium is also increasing rapidly. For example, 12-Mbyte and 1-Gbyte products are available as card-like recording media, and a magnetooptical disk having a recording capacity of several ten Gbytes, and a hard disk having a recording capacity of several hundred Gbytes can be realized with low cost. For this reason, a recordable time and the number of files that can be recorded are increasing year by year.
Nowadays, the capacities of data recording media such as memory cards used in digital cameras, optical disks used in digital video cameras, and the like are increasing remarkably, and various data such as moving image data, audio data, still image data, and the like can be recorded. Also, many products using these recording media are available. In these products, an edit function of re-arranging or combining recorded contents by exploiting random access that cannot be attained by a video tape is one of the features of such product.
The edit function includes an erase function of erasing unnecessary contents, a partial erase function of designating and deleting an unnecessary part from contents, and functions of actually editing contents data (e.g., division and combination of contents). Also, a method of recording playback control information such as a playback sequence, layout, and the like, and reading out and playing back data according to this playback control information in a playback mode is known. Such method is an edit function called a playlist.
In order to implement this playlist, a method disclosed in Japanese Patent Laid-Open No. 2000-187963 may be used. With this method, data to be played back is designated by a pointer to a playback time map table. The playback time map table indicates the start position of each decode unit of MPEG (Moving Picture Experts Group). However, with this method, the description method of playback control information adopts a very limited format, and does not allow any flexible description. Also, only a compatible device or computer software can implement a playback process according to the playback control information.
When an application 1700 directly accesses files on a recording medium 1702 using a file system 1701 as in a conventional system shown in FIG. 17, if the number of files or the number of groups increases, it becomes difficult to simultaneously manage them, and it takes long time to retrieve necessary information. Furthermore, when a file is specified via a file system (a structure system including management information used to manage files and file data), the type of file can be determined based only on an extension, and video and audio files with the same type of extension can hardly be identified, thus disturbing quick search.
In order to time-serially play back a plurality of files recorded on the recording medium, all recorded files must be accessed to re-sort them in the order of their recording times. In this case, time-series information may be held by devising the directory structure or file names. However, the degree of freedom in the directory structure or file names lowers, resulting in inconvenience in terms of file management.
When the aforementioned management file is used, it must be created for each group. For this reason, in order to detect information such as members or the like included in each management file, management files must be opened and checked one by one, thus requiring troublesome, inconvenient processes. In addition, management files have different formats for respective applications that use them, and cannot be used by a different application, resulting in poor compatibility.
When each individual management file is used, access to respective files recorded on the recording medium is directly made by an application using the file system. Hence, a problem of the process that takes a long time to retrieve necessary information remains unsolved.
As for the playlist, upon displaying a reference designation file (contents) list which is referred to and designated by the playlist, or upon locking a reference designation file (contents) by a system, that playlist must be interpreted. Hence, an apparatus which does not have any playlist playback function cannot detect a reference designation file in a playlist created by another apparatus, and an appropriate warning message cannot be displayed when the user erases contents.